For instance, if you are running 20 miles every week, your next week’s run should be increased to no more than 22 miles. Following this simple rule helps keep common overuse injuries at bay.

Gives You Your Best Shot of Finishing

If you enter a half marathon and the longest run you’ve done before that is 8 miles, you’re in for a rude awakening. You might not be able to finish your race.

If you haven’t done a longer run, you’re going to have a much harder time getting past that finish line.

While you don’t have to run 13 miles in your training runs in order to finish a half marathon, it’s a good idea to get up to 11 miles to give you the confidence and stamina you’ll need to log 13.1 on race day.

Avoids Some Pain

Even if you don’t injure yourself by running a half marathon when you aren’t fully prepared, it’s not going to be a pleasant experience. The next day, you’ll be kicking yourself if you could just get your legs to move.

Even when you do train for a half marathon, you’ll generally be feeling it the next day, but that discomfort will be made much worse by inadequate training.

Running a Half Marathon in 6 Weeks

If you decide to go ahead with your plan to run a half marathon in 6 weeks, here are some tips you should follow to ensure your plan doesn’t evaporate mid-run on race day.

Use Caution if You’re a Rookie

If you have never even run a single mile and you’ve decided you want to run a half marathon with only six weeks of training, reconsider your plan, unless you plan to walk a good share of the distance. You simply aren’t ready for a plan this ambitious -- consider a 12-week plan instead.

Remember when we talked about injuries earlier? If you put your 6-week plan in motion, you’re playing with fire.